How to sort HashSet in Java



To sort HashSet in Java, you can use another class, which is TreeSet.

Following is the code to sort HashSet in Java −

Example

 Live Demo

import java.util.*;
public class Main {
   public static void main(String args[]) {
      Set<String> hashSet = new HashSet<String>();
      hashSet.add("green");
      hashSet.add("blue");
      hashSet.add("red");
      hashSet.add("cyan");
      hashSet.add("orange");
      hashSet.add("green");
      System.out.println("HashSet elements
"+ hashSet);       Set<String> treeSet = new TreeSet<String>(hashSet);       System.out.println("Sorted elements
"+ treeSet);    } }

Output

HashSet elements
[red, orange, green, blue, cyan]
Sorted elements
[blue, cyan, green, orange, red]

Let us see another example wherein we will sort the HashSet in descending order using Collections.sort() method with reverseOrder() method −

Example

 Live Demo

import java.util.*;
public class Main {
   public static void main(String args[]) {
      Set<String> hashSet = new HashSet<String>();
      hashSet.add("yellow");
      hashSet.add("green");
      hashSet.add("blue");
      hashSet.add("cyan");
      hashSet.add("orange");
      hashSet.add("green");
      System.out.println("HashSet elements
"+ hashSet);       List<String> myList = new ArrayList<String>(hashSet);       Collections.sort(myList,Collections.reverseOrder());       System.out.println("Sorted (descending order)
"+ myList);    } }

Output

HashSet elements
[orange, green, blue, yellow, cyan]
Sorted (descending order)
[yellow, orange, green, cyan, blue]

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